LuduminaPM-04 · PM-U2 · Planned
Changes of state and latent heat
Learning objectives
Explain reversible state changes and mass conservation; calculate latent energy; interpret heating/cooling plateaux.
8463 §§4.3.1.2,4.3.2.3 / 8464 §§6.3.1.2,6.3.2.3
DfE single-science pp.42–43 / Combined pp.35. Evidence checked 30 September–1 October 2026. Skills: WS1.2,3.5; MS3c,3d,4a.
Needs firstPM-03
Explanation
During a state change, energy changes particle separation/interaction potential energy while temperature can remain constant. Specific latent heat is energy per kilogram for that change. In ordinary reversible state changes, total mass is conserved.
Concepts, equations and units: E=mL; J,kg,L in J/kg; latent fusion/vaporisation; constant-temperature phase change at stated pressure.
Prediction, demonstration and game exercise
Predict, observe, explain
Heat a fixed mass through melting and boiling; reveal energy input with constant-temperature intervals.
Planned learner game exercise
Allocate energy to a sample across states; label solid, liquid, gas and mixed-phase intervals.
Independent practice
Three latent-heat calculations and a temperature–time graph explanation, including cooling.
Original practice example · Shared
Melt 0.20 kg of a solid with latent heat 100,000 J/kg at its melting point. Find energy required.
Show working and model answer
Working / reasoning
E = mL = 0.20 × 100,000.
Answer
20,000 J.
Exit check and success criteria
Two values correct, plateau linked to potential-energy change and mass conserved.
During practice, compare the prediction with evidence and give an error-specific prompt. The exit item uses a fresh context or fresh values, answered independently.
Misconceptions, practical links and mastery
Check these misconceptions
Temperature always rises when heating; particles vanish on evaporation; latent heat means no energy transfer.
Practical preparation
Optional teacher-supervised heating/cooling demonstration; not an RP.
Virtual preparation and revision only. Required hands-on activities and school records remain separate.
Proposed mastery
0: not yet evidenced. 1: supported. 2: independent exit criteria met. 3: successful changed-context transfer. Advance at 2; revisit with fresh retrieval. These are not GCSE grades.